This report describes the typical weather at the Henry E. Rohlsen Airport (St. Croix, US Virgin Islands) weather station over the course of an average December. It is based on the historical records from 1991 to 2012. Earlier records are either unavailable or unreliable.
St. Croix has a tropical savanna climate with dry winters. The area within 25 mi of this station is covered by oceans and seas (96%) and forests (2%).
The month of December is characterized by essentially constant daily high temperatures, with daily highs around 84Â°F throughout the month, exceeding 87Â°F or dropping below 81Â°F only one day in ten.
Over the course of December, the length of the day is essentially constant. The shortest day of the month is December 27 with 11:04 hours of daylight; the longest day is December 1 with 11:10 hours of daylight.
The earliest sunrise is at 6:34am on December 1; the latest sunset is at 5:55pm on December 31; the latest sunrise is at 6:50am on December 31; the earliest sunset is at 5:43pm on December 2.
Daylight saving time (DST) is not observed in 2012.
The median cloud cover is 42% (partly cloudy) and does not vary substantially over the course of the month.
On December 16, a representative day, the sky is clear or mostly clear 38% of the time, partly cloudy 24% of the time, and mostly cloudy or overcast 21% of the time.
The probability that precipitation will be observed at this location varies throughout the month. Precipitation is most likely around December 1, occurring in 45% of days. Precipitation is least likely around December 17, occurring in 41% of days.
Throughout December, the most common forms of precipitation are light rain, moderate rain, and heavy rain.
Light rain is the most severe precipitation observed during 55% of those days with precipitation. It is most likely around December 23, when it is observed during 24% of all days.
Moderate rain is the most severe precipitation observed during 27% of those days with precipitation. It is most likely around December 1, when it is observed during 12% of all days.
Heavy rain is the most severe precipitation observed during 14% of those days with precipitation. It is most likely around December 1, when it is observed during 7% of all days.
Either snow is exceptionally unlikely to fall at this location in December or this station does not reliably report precipitation types.
The relative humidity typically ranges from 63% (mildly humid) to 89% (very humid) over the course of a typical December, rarely dropping below 55% (mildly humid) and reaching as high as 97% (very humid).
The air is driest around December 24, at which time the relative humidity drops below 67% (mildly humid) three days out of four; it is most humid around December 11, rising above 85% (humid) three days out of four.
Dew point is often a better measure of how comfortable a person will find the weather than relative humidity because it more directly relates to whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid.
Over the course of a typical December, the dew point typically varies from 67Â°F (muggy) to 73Â°F (very muggy) and is rarely below 64Â°F (mildy humid) or above 76Â°F (oppressive).
Over the course of December typical wind speeds vary from 6 mph to 17 mph (light breeze to moderate breeze), rarely exceeding 22 mph (fresh breeze).
The highest average wind speed of 11 mph (gentle breeze) occurs around December 31, at which time the average daily maximum wind speed is 17 mph (moderate breeze).
The lowest average wind speed of 10 mph (gentle breeze) occurs around December 11, at which time the average daily maximum wind speed is 17 mph (moderate breeze).